Linos et al (2011) used an ecologic design and therefore the study has significant limitations noted in the paper. Based on small numbers of exposed population, the exposure is expressed as residing in the area assuming that all residents consumed water provided by the municipality, but no individual exposure data was availalbe. The study is hypothesis-generating and not very informative with regard to the role of Cr-VI given the ecologic design and potential confounding factors. The authors conclude:

“Water contaminated with hexavalent chromium has been suggested as a potentialcarcinogen in humans through the oral route. This study provides further evidence of this relationship. In light of the potentially widespread health implications of such contamination, further studies are critically needed to explore the possible causal link between exposure to hexavalent chromium through drinking water and cancer risk. Such evidence is needed to establish guidelines for the prevention of this form of contamination and formulate public health recommendations.”